On the heels of Southern California’s big rains, residents now can expect the downside: an early and vicious mosquito season.

Spring is here and the swarms of invasive Aedes mosquitoes that caused so much grief in 2018 are expected to return with a vengeance following this winter’s heavy rains.

Vector control officials in Los Angeles and Orange counties are bracing for what they expect will be a busy year. Since arriving in Southern California in 2011, the tiny “ankle biter” insects have been multiplying every year.

“Since then, we’ve seen a total of three new Aedes species and they are continuing to spread and expand their ranges,” said Kelly Middleton, director of community affairs for the Greater Los Angeles Vector Control District.

“They moved up into the San Fernando Valley and we started to get a lot more calls from that area last year,” Middleton said, adding that Whittier and Lakewood were other areas reporting problems. “Once they move in, the populations (at first) are low but they build up pretty quickly.”

Orange County is anticipating 20 percent increase in resident calls this year — along with a population growth and spread.

“We’re anticipating some increase in Aedes mosquito in Orange County just because of the recent rains and (additional) backyard sources collecting water,” said Lora Young, director of communications for Orange County Mosquito and Vector Control District. The mosquitoes made their first appearance in Orange County in 2015 in Mission Viejo but since then has gained a solid foothold. They’ve also been recorded in San Gabriel Valley.

Because immune systems aren’t used to the invader, the bites have spawned long social media threads along with doctor and urgent care visits for prescription help. Facebook posts from San Pedro and Long Beach exploded last year with posters wondering what was delivering the dozens of repeated, pinpoint bites that ballooned into huge, red welts and were making them so miserable.

And if the bites weren’t punishing enough, these particular mosquitoes also can spread diseases including Zika, yellow fever, chikungunya and dengue that have authorities particularly concerned.

So far, there have been no indications of infected mosquitoes in collected samples from Los Angeles or Orange counties.

There are a number of differences between the Aedes mosquitoes and California’s native nocturnal variety, the Culex (“southern house”) mosquito, that spreads West Nile Virus.

Culex mosquitoes prefer to bite birds, not people, and are easy to detect because of their large size and loud buzzing.

Aedes species mosquitoes are aggressive, daytime biters that prefer to bite people. They often fly low to the ground to feast on legs, ankles and feet, including toes, leaving multiple welts. And they are so tiny that most people never even see what bit them leading to speculation that so-called “no-see-um” sand mites (not common in this region) or other pests might be to blame.

“They’re very stealthy and small so you don’t hear them or see them,” Middleton said. “They sneak up behind you.”

“These mosquitoes fly lower, that’s how they got dubbed the ‘ankle biters,’” Young said, adding that most people have severe reactions to the bites.

After last year’s uptick in activity, some Vector Control agencies considered launching a neighborhood-watch style program this summer that would have provided residents with mosquito traps to monitor. An early outreach was conducted via the NextDoor social media app seeking participants, but Middleton said the effort ultimately was dropped since the traps rely heavily on people emptying the larvacide and water regularly. If that’s not done religiously, she said, the larvacide loses strength and the water then can become an attractant that would only make conditions worse in those neighborhoods.

But help may be coming from a group of AP physics high school students who are designing a better mosquito trap.

The invention from Los Altos High School in Hacienda Heights has made it into the national finals for the Samsung Solve for Tomorrow competition and will compete against nine other high school entries in New York April 1-2.

The impetus for choosing their project?

“Some of the teachers and students mentioned that they were getting mosquito bites in their classroom,” said their teacher, Paul Fang.

Nineteen students are working on the entry for the nationwide competition that challenges students in grades 6-12 to use STEM (science, technology, engineering and math) skills to address local issues and inspire change in their communities.

But Middleton said the fight against mosquitoes is one that probably won’t be won anytime soon.

“The bottom line is we’ve been trying to control mosquito populations historically forever,” Middleton said. “They’ve been on this planet since the age of the dinosaurs. … All we can do is keep the numbers down.”

“We’re really stressing that this is a problem that’s here to stay,” Young said. “This is a whole new species that’s impacting our quality of life.”

Donna Littlejohn has covered the Harbor Area as a reporter since 1981. Along with development, politics, coyotes, battleships and crime, she writes features that have spotlighted an array of topics, from an alligator on the loose in a city park to the modern-day cowboys who own the trails on the Palos Verdes Peninsula. She loves border collies and Aussie dogs, cats, early California Craftsman architecture and most surviving old stuff. She imagines the 1970s redevelopment sweep that leveled so much of San Pedro's historic waterfront district as very sad.